Heat exchanger baffle tube
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In the heat exchangers, some were found to have tube supports and dummy tubes; I wonder if their function is to provide fixation.
The author’s view seems incorrect; generally, baffle tubes and dummy tubes are used in U-tube heat exchangers. Their main function is to prevent bypass flow and enhance heat transfer. Since there is usually a large gap in the middle part of U-tubes, it is the baffles and support plates that serve to provide fixation and support. This post was last edited by jia717 on 2009-3-2 19:36]
Heat exchanger baffle tubes and dummy tubes serve mainly to prevent fluid short circuits and enhance heat transfer; there are also forms such as bypass baffles and intermediate baffles
In multi-pass heat exchangers, in order to prevent the fluid from flowing directly between the passes without passing through the heat exchange tubes, artificial tube resistance must be created so that the fluid flows as closely as possible alongside the heat exchange tubes for heat exchange. The false tube prevents bypass flow of the shell-side fluid, and its ends must be sealed
In fixed-tube-sheet heat exchangers, when the tube string is located on the tie rods, in the middle of the baffle plates, this serves to fix the baffle plates in place
What I mentioned is definitely a fixed-tube-sheet heat exchanger
In the flow path analysis method proposed by Tinker, the fluid in the shell side is divided into 5 streams; one of these streams occupies the space behind the partition plates that run parallel to the flow direction. There are no tubes in this area, so the heat exchange efficiency decreases. Fake tubes are installed to ensure that the fluid in this area also remains in a turbulent state, thereby improving the heat exchange efficiency and reducing the negative impact of this flow path on it
What was said on the 7th floor is very correct; fixed-tube-sheet designs definitely come with partition plates. However, in the case of U-tube designs, the spacing between the tubes in the middle is significantly larger compared to fixed-tube-sheet designs. In our designs, we usually use dummy tubes (shields) in U-tube designs to prevent fluid short-circuiting and to increase the heat transfer coefficient.
In shell-and-tube heat exchangers, spiral baffle plates are used to prevent fluid short-circuiting, which improves the heat transfer coefficient and enhances heat transfer efficiency significantly.
The same principle applies when using fixed tube sheets in multi-pass heat exchangers; a few days ago I saw in the workshop tubes with supports (dummy tubes), with one such support provided for every four rows of tubes.
What serves a fixing role are the tie rods and baffle plates, as well as the support plates in U-tube heat exchangers. The tube baffles and dummy tubes in heat exchangers, as well as bypass baffles and intermediate baffles, serve primarily to prevent fluid short-circuiting and to enhance heat transfer.
Could you explain it in simpler terms? I really don’t understand it. . .
Take a look at GB 151-1999 for shell-and-tube heat exchangers; it provides detailed information on that topic.
The function of the pipe baffles and shields is to install shields as required for unidirectional flow per GB151, in order to prevent short-circuiting of the unidirectional flow and to allow as much of the heat exchange medium as possible to flow through the heat exchange tubes, thereby improving the heat exchange efficiency
May I ask, why are the tubes blocked at both ends? 151 requires both ends, while some sources mention just one end.